Electrical circuit breaker for an



Dot. 9, 1956 ELECTRICAL 1.. G. zoccl-n 2,766,337

CIRCUIT BREAKER FOR AN INTERNAL COMBUSTION ENGINE Filed Oct. 9, 1953 INVENTOR. Leon. G. Zoccl'u United States Patent ELECTRICAL CIRCUIT BREAKER FOR AN INTERNAL COMBUSTION ENGINE Leon G. Zocchi, Milford, Mass. Application October 9, 1953, Serial No. 385,127 1 Claim. (Cl. 200-21) This invention relates to the circuit breaker for the direct current primary of an induction coil in the spark generating system of an internal combustion engine.

In the standard circuit breaker system, a rotary cam carried by the distributor housing is arranged to move one electrical contact relative to another and make and break the primary coil circuit in a batery ignition system and thereby create a high voltage alternating current in the secondary circuit which leads to the engine spark plugs arranged for igniting the fuel. One circuit breaker is held stationary on an adjustable contact plate carried by the housing while the other contact is carried by a pivoted arm which is resiliently urged toward the stationary contact. That arm has a cam follower engaging the engine rotated cam which serves to move the arm and break and make the primary circuit once per cam cycle or follower movement past each high point of the cam. The contact plate is also mounted to be rotated through a small angle relative to the cam so that for the higher engine speeds the spark may be advanced in its timing cycle.

I have found that at high speeds there is not time enough to build up suflicient curent in the primary to produce a satisfactory spark in the secondary system during the interval while the contacts are touching, with the result that the engine does not run economically at the higher speeds. In a six cylinder engine driving a car at 80 miles per hour, the coil must furnish 12,000 sparks per minute or 200 every second. The contacts, however, need to be held closed long enough to accumulate a sufiicient condenser charge for creating a heavy spark, and this requires that the contacts remain closed for at least 0.001 to 0.0015 part of a second. The time of contact is determined primarily by the time during which the cam is not in contact with the follower which opens the contact gap. Also, the inertia in the outwardly flying contact arm may cause it to travel too far and leave the contacts separated more than the time allowed for breaking the circuit. The breaker contacts in a standard six cylinder engine are customarily set at a spacing of 0.025 inch for all standard speeds, but the requirement for moving the contacts through even that short distance wastes so much time in closing the circuit that the cam must again separate the contacts before the required time for building the spark has elapsed. Hence the time period of separation of the contacts is important and that period should be decreased relative to the cam movement as the engine speed increases, or the relative percentage of time during which the cam follower is out of contact with the contact actuating cam should be increased. This is a relative relationship in which the time of contact engagement is a function of the angular distance of cam movement relative to the follower while the contacts are closed.

It is the primary object of my invention to overcome that problem and to provide adequate time, as the speed of the engine driven cam is increased, for accumulating ,7 2,766,337 l atented Oct. 9, 1956 the spark producing charge and thus provide a hotter and more intense spark and a more eflicient operation of the engine at high speeds. Further objects will be apparent in the following disclosure.

In accordance with my invention, I decrease the maximum contact gap as the engine sped increases and so consume less time during which the contacts are being opened and provide a greater relative time during which they remain closed. To this end, I mount the two rela tively movable contacts on a plate which is moved relative to the rotary cam, as the cam speed is increased by the engine, to reduce the gap distance and the time of contact of the cam follower with the engine rotated cam and thereby increase the relative time during which the contacts remain engaged. The movable plate which carries the contacts or points may be moved either automatically or by manually operated mechanism which serves to lessen the contact gap progressively as the motor speed or rotation rate of the cam increases.

Referring to the drawings illustrating my invention:

Fig. 1 is a top plan view of the primary circuit breaker and associated parts, which shows the circuit gap at a maximum for a slow speed;

Fig. 2 is a fragmentary vertical elevation of the housing and circuit breaker, taken on the line 22 of Fig. 1; and

Fig. 3 is a plan view, partly broken away, corresponding with Fig. 1 which shows the narrower gap provided for a high speed engine movement.

In the construction of Figs. 1 to 3, a vertical shaft 10 is rotatably mounted in the distributor and breaker housing 11, and a horizontal contact carrier plate 12 is mounted for rotation about the shaft 10 located centrally of the plate. The shaft 10 carries a cam 14 having the required number of high points, such as six, corresponding with the number of engine cylinders or spark plugs in the secondary circuit. The cam is arranged to contact a cam follower 15 on an arm 16 pivoted to swing horizontally about a vertical post 18 carried by an adjustable contact plate 20 mounted on the rotary carrier plate 12. An electrical contact or point 22 on the outer end of the swinging arm 16 is arranged to make and break contact with a stationary contact member or point 23 carried by a lug 24 projecting vertically from the relatively fixed but adjustably mounted plate 20. The fol lower 15 is so located that it is struck by the higher parts of the cam and thus serves to swing the arm 16 and separate the contacts 22 and 23. The contact 23 is grounded through the metal plates 12 and 20 and the housing 11. The contact 22 is connected into the primary coil circuit through a wire 25 connected by a bolt or a binder post 26 and nut to a leaf spring 28 which is fixed at one end by the post 26 to the adjustable plate 16. The other end of the spring 28 is suitably fixed to the swinging arm and so arranged that it resiliently urges the contacts 22 and 23 into engagement, when the follower is opposite a low portion of the multiple cam 14. When the follower is on a high point of the cam, as shown in Fig. 1, the contacts 22 and 23 have their maximum separation.

The swinging arm 16 cannot move outwardly to produce more than a predetermined maximum separation of the contacts because of the engagement of a button or part 30 on the arm striking a lug 31 on the side of the standard 32 which carries the spring connection and binder post 26. The lug 31 may be the head of the post 26 which is suitably insulated from the plate 16 so that the electric current cannot be short circuited into the plate. The button 30 and lug 31 are arranged to contact when the follower 15 is on a high point of the cam when the engine is running at a comparatively slow speed, as

shown in Fig. 1. To this end, the plate 20 is pivoted on the rotary plate 12 by means of a set screw 34', and a set screw 35 carried by plate 12 rides in an elongated slot in the plate 20 and serves for adjustably clamping the plate 20 in such a position that the cam follower jllSt contacts the high point of the cam 14 when the required gap separation between the contacts is had, such as 0.025 inch for a slow speed of the engine. For that adjusted position, the parts 30 and 31 are substantially in engagement and prevent any overthrow of the pivoted arm 16, as is more fully described and claimed in my copending Patent No. 2,713,094 of July 12, 1955.

A standard construction comprises mechanism for advancing the spark. As indicated in Fig. 1, this is effected by means of a vacuum actuated diaphragm 40 which is moved in accordance with an increase of vacuum applied through the pipeline 41 from the carburetor. This moves a rod 42 which is pivotally connected to the carrier plate 12 and thus rotates that plate counter-clockwise as the vacuum increases. This serves to advance the cam follower 15 counter to the direction of cam rotation and against the tension of a tension coil spring 43 connecting a post 44 on the plate 12 and a post 45 on the housing base which projects through an elongated slot 46 in the plate 12. This advancement of the spark by the relative iovernent of the cam follower and cam, however, does not affect the distance of separation of the contacts 22 and 23, since the cam follower 15 is advanced in a circle concentric with the cam.

In accordance with my invention I propose to move the cam follower 15 away from the cam 14 as the engine speed increases so as to shorten the contact gap at the high point of the cam relative to the contact moving camshaft 12 by mechanism which serves to reduce the contact gap progressively as the motor speed increases. This plate movement, which may be caused by a manual adjustment of the position of plate 20, is preferably effected automatically and by the same vacuum actuated diaphragm which advances the spark, or a similar device. To this end, I mount the plate 12 (Fig. 2) on a cylindrical bearing or bushing 48 having its external surface eccentric to the camshaft 10, so that when the plate 12 is rotated to advance the spark, it turns on its eccentric bushing 48 and moves the plate 20 and the cam follower 15 away from the rotating cam 14. Thus, the vacuum operated diaphragm serves the double function of advancing the spark and reducing the gap as the vacuum is increased. That is, the vacuum operated diaphragm swings the plate 20 about the eccentric bearing in a direction opposite to that in which the contact moving cam is rotating and thereby moves the cam follower 15 away from the cam sufficiently to reduce the gap distance. The follower 15 does not engage the cam 14 except near the high points and this shortens the angular distance through which the swinging follower 15 touches the cam 14 and so lengthens the time during which the contacts 22, 23 are in engagement. The eccentricity of the bushing 48 and the location of the thickest portion of this cylindrical body 48 is such that the maximum gap separation for a normal setting, such as 0.025 inch for the engine at slow speed, may be reduced by as much as 25 to 50% or more as the speed is increased. I have found that for a very high speed an adequate spark is obtained when the gap is as little as 0.006 inch. The plate 12 is fixed to a depending sleeve 49 having an inner cylindrical bearing rotatably mounted on the outer cylindrical surface of the eccentrically positioned stationary sleeve 48 within which the camshaft rotates. The inner sleeve 48 is suitably mounted in a recess in the housing base and secured in place, as by friction. Thus, rotation of the plate 12 moves the cam follower away from the cam 14. Thus the distance of movement of the movable contact 22 by the follower 15 becomes progressively less and the gap decreases likewise progressively. This serves to save time in moving the contact 22 and increase the time interval during which the contact points 22, 23 are touching the speed of engine movement increases. This gives the coil and condenser system of the primary induction circuit more time to build up adequate capacity to create the spark in the secondary circuit. This results in an economy of use of gasoline at the higher engine speeds and gives a more efficient operation of the engine.

In its operatiomplate 12 of Fig. 1 is normally rotated by the increase of vacuum inthe carburetor system as the engine speed increases and this serves to advance the timing of the spark in the engine cylinder. In the prior art practice, the gap between the breaker contacts has remained the same while advancing the spark, or in fact it has even become accidentally increased due to the momentum of the rapidly flying contact arm 16. The eccentric bushing 48 is so oriented that the arm 16 and contact 15 are automatically moved away from the cam by that same rotation of the plate 12 as the speed increases. This' increases the percentage of the time of con tact of points 22 and 23 in a single cam rotation, or it decreases the angular distance during which the follower touches the cam during its movement between two high points of the cam. Thus the engine efficiency is increased not only by advancing the spark timing but by shortening the angular distance through which the follower 15 touches the cam 14, thus increasing the relative time during which contacts 22 and 23 remain closed. This reduction of movement of the contact arm also aids in reducing the wear on the cam and cam follower because of the cam follower being out of contact with the cam for an increasing time as the engine speed increases.

It will now be appreciated that various modifications may be made within the scope of my invention and that the above description of the principles and preferred embodiments of the invention are not to be interpreted as imposing limitations on the appended claim.

I claim:

A distributor and circuit breaker for the electrical ignition circuit of an internal combustion engine comprising a housing, a camshaft projecting into the housing which is rotated at an engine governed rate varying from a normal low to a high speed, a timing cam on the shaft, a bushing which bears on the shaft and is fixed on the housing, said bushing having an external bearing surface eccentric to and surrounding the shaft, a rotary carrier plate having a sleeve bearing on said eccentric surface, a contact plate, means for adjustably mounting the contact plate on the rotary carrier plate to vary its distance from the cam, a resiliently urged arm pivoted on the contact plate, a stationary contact on the contact plate and a swinging contact on the arm arranged to provide a spark gap for making and breaking the circuit, a cam follower for said cam on the arm, the contact plate adjustment serving to locate the follower relative to a high point of the cam and provide a definite maximum width of spark gap for a slow engine speed, a pressure actuated dia phragm responsive to an increase in the engine speed, and means connecting the diaphragm with the rotary carrier plate which revolves the contact plate about the camshaft as the engine speed increases so as to advance the spark, the movement of the contact plate around the eccentric bushing serving to move the cam follower away from the cam axis and thus decrease the angular distance of contact of the follower with the cam and decrease the maximum width of the spark gap, said eccentricity of the bushing providing for a decrease in the width of the spark gap of at least 25% to 50% of the gap employed for slow speed rotation.

References Cited in the file of this patent 

